Fix for broken BC through #1503: The slice filter works as the array_slice PHP function for arrays

lib/Twig/Extension/Core.php

@@ -708,7 +708,11 @@ function twig_slice(Twig_Environment $env, $item, $start, $length = null, $prese
         }
 
         if ($start >= 0 && $length >= 0) {
-            return iterator_to_array(new LimitIterator($item, $start, $length === null ? -1 : $length), $preserveKeys);
+            try {
+                return iterator_to_array(new LimitIterator($item, $start, $length === null ? -1 : $length), $preserveKeys);
+            } catch (\OutOfBoundsException $exception) {
+                return array();
+            }
         }
 
         $item = iterator_to_array($item, $preserveKeys);

test/Twig/Tests/Fixtures/filters/slice.test

@@ -13,6 +13,8 @@
 {{ '1234'[1:2] }}
 {{ arr|slice(1, 2)|join('') }}
 {{ arr[1:2]|join('') }}
+{{ arr[4:1]|join('') }}
+{{ arr[3:2]|join('') }}
 
 {{ [1, 2, 3, 4]|slice(1)|join('') }}
 {{ [1, 2, 3, 4][1:]|join('') }}
@@ -38,6 +40,8 @@ bc
 23
 23
 
+4
+
 234
 234
 234